Emscripten tag in wheels (`emscripten_4_0_9`)

Packaging
1

I beleive I’ve come across emscripten_4_0_9_wasm32 tags in pyodide wheels before, but it seems now all wheels in pyodide use strictly pyodide tag (e.g. pyodide_2025_0_wasm32.whl) and I’ve seen emscripten tag only as some intermediate step during pyodide build.

Sorry, if it’s a dumb question, but what emscripten_4_0_9 tag is for, is it still used?

Is it the one that would be used if someone would build a package for original CPython that was compiled to emscripten without any modifications?

Are there this kind of packages out there or it’s currently more of a theorethical possibility?

2

PEP 783 – Emscripten Packaging | peps.python.org might have more details, otherwise @hoodmane should know.

3

Pyodide currently accepts either emscripten_4_0_9_wasm32 or pyodide_2025_0_wasm32. The practical reason was that we originally made wheels with the first tag then later switched to the second. Since there was still tooling around producing the first tag, we needed to accept both.